[dm-crypt] Fuzzing

Arno Wagner arno at wagner.name
Mon Apr 11 20:26:16 CEST 2016

I don't really think so. Fuzzing is good to find non-obscure 
bugs and authorization problems. There is no authorization
in cryptsetup because the user executing cryptsetup has
full controll over the code and the machine anyways.

And while cryptsetup surely has some errors left, I think most 
of them are either obscure or end up here anyways and get fixed.
If nobody runs into bugs, then they do not matter unless they
are in some software that protects some kind of perimeter.
Cryptsetup does not protect any perimeter.

Just my take on this, others may disagree.

Note that filesystems and more generally datastructures
are very good targets for fuzzing or randomized testing.
I have made excellent experiences with that. But they are
different. If cryptsetup works wrongly, you do not get
an unlocked container. That is blatantly obvious. If a 
datastructure or filesystem works wrongly, you get subtle
errors and corruption that you may not notice for a long 


On Mon, Apr 11, 2016 at 17:42:19 CEST, Lars Winterfeld wrote:
> Hi,
> I just stumbled upon those slides, where they test file system code in
> the linux kernel (ext4, btrfs, xfs, ...) using a fuzzing method (they do
> find bugs):
> http://events.linuxfoundation.org/sites/events/files/slides/AFL%20filesystem%20fuzzing%2C%20Vault%202016.pdf
> I have not studied it in detail, but it looks like they used the open
> source "American Fuzzy Lop" (afl, written for userland code) and got
> some ideas how to employ it for kernel code.
> Could this perhaps be used to test some parts of cryptsetup?
> Best wishes,
> Lars

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Arno Wagner,     Dr. sc. techn., Dipl. Inform.,    Email: arno at wagner.name
GnuPG: ID: CB5D9718  FP: 12D6 C03B 1B30 33BB 13CF  B774 E35C 5FA1 CB5D 9718
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